咪唑类离子液体溶解纤维素的研究进展

综述了1-丁基-3-甲基咪唑氯盐、1-烯丙基-3-甲基咪唑氯盐、1-(2-羟乙基)-3-甲基咪唑氯盐等咪唑类离子液体对纤维素的溶解性能,咪唑类离子液体/纤维素溶液的流变性能以及咪唑类离子液体在纤维素纤维及薄膜加工中的应用;咪唑类离子液体均能较好地溶解纤维素,咪唑类离子液体/纤维素溶液均为切力变稀流体;指出选择合适的阴、...     

Synthesis of cyclic carbonate from vinyl cyclohexene oxide and CO2 using ionic liquids as catalysts

Synthesis of cyclic carbonate from 4-vinyl-1-cyclohexene-1,2-epoxide (VCHO) and carbon dioxide was investigated without using any solvent in the presence of ionic liquid as a catalyst. Ionic liquids based on 1-alkylmethylimidazolium salts of different alkyl groups (ethyl, butyl, hexyl, octyl) and different anions (Cl⁻, BF₄⁻, PF₆⁻) were used as catalysts. The conversion of VCHO was affected by the structure of the imidazolium salt ionic liquids; the ones with the cations of bulkier alkyl chain length and with more nucleophilic anion showed better reactivity. Reaction temperature, carbon dioxide pressure, and zinc halide cocatalyst enhanced the addition of CO₂ to VCHO. Semi-batch operation with continuous supply of carbon dioxide showed higher VCHO conversion than batch operation did.     

基于离子液体的“可设计性”和“软酸”性质萃取分离电镀污泥中Cr6+/Fe3+

基于离子液体的"可设计性"和"软酸"性质对于其在电镀污泥酸浸液中铬铁萃取分离方面的应用及其机理进行研究。结果表明：咪唑环上烷基链的长度对于铬铁萃取分离效果有较大的影响,阴离子为[BF₄]^-的离子液体对于铬铁萃取分离能力大于阴离子为[PF₆]^-的离子液体。在所研究的离子液体中,[Omim] [BF₄]对于铬铁具有较好的萃取分离效果,实现了电镀污泥中铬铁分离。结合斜率法、红外光谱分析、Raman光谱分析,[Omim] [BF₄]萃取铬符合离子缔合机理,可推测[Omim] [BF₄]咪唑阳离子与Cr₂O₇^2-阴离子形成离子缔合物而进入有机相,达到萃取分离,从而实现电镀污泥资源化目的,具有一定的应用性。     

胶原在两种离子液体[BMIM]Cl和[BMIM]Ac中的溶解及再生结构比较

采用离子交换法, 以1-丁基-3-甲基氯代咪唑([BMIM]Cl)为原料合成了咪唑醋酸盐型离子液体([BMIM]Ac), 以两者为溶剂研究了胶原纤维在咪唑类离子液体中的溶解行为及再生前后的结构与热稳定性变化。结果表明, 胶原纤维在CH₃COO^-和Cl^-型离子液体中均能溶解, 但具有明显不同的溶解特性。相对[BMIM]Cl的溶解性能而言, [BMIM]Ac能够在较低的温度下获得高浓度和良好流动性的胶原溶液, 而且再生胶原的三股螺旋结构保留度更高。FTIR、UV、XRD、CD、TG分析结果表明, 胶原在咪唑离子液体中溶解前后其化学结构未发生明显变化, 而三股螺旋的保留度和热稳定性略有降低。     

Removal of mercaptans from light oils using ionic liquid–NaOH aqueous solution as extractants

The application of ionic liquids as alternatives to conventional organic solvents in the extraction process has been investigated. In the present study, fourteen species of imidazolium-based ionic liquids were added into the Na OH(aq) to remove the mercaptans. The influences of anion species and cation alkyl chain length of the imidazolium-based ionic liquids on the performance of mercaptan removal from light oils have been discussed.The efficiency of extraction for mercaptans exhibited the order of [Ac]~-N [OH]~-≈ [Br]~-N [BF4]~-. The longer alkyl chain imidazolium-based ionic liquids contributed to enhance desulfurization rate of 1-butyl mercaptan.100% desulfurization rate of 1-butyl mercaptan was achieved by the anion of Ac-ionic liquids and Na OH(aq)at a volume ratio of 40:1(V(oil):V(ionic liquid)) and a short equilibrium time within 10 min.     

咪唑类离子液体合成及其应用研究

介绍了咪唑类离子液体的一般性质和合成方法,及其作为一种新型的化学溶剂广泛应用于化学合成、分离过程和电化学等方面,具有良好的发展前景。     

离子液体中胰岛素结构稳定性的分子动力学模拟

离子液体作为一种新型绿色溶剂,由于其独特的物理化学性质,被广泛应用于蛋白质的稳定性研究。选用热敏性蛋白药物胰岛素作为研究对象,采用分子动力学模拟方法,从分子层面上研究不同种类的离子液体对胰岛素结构的稳定效果。结果表明,与纯水体系相比,在常温下离子液体能够有效地稳定胰岛素的分子结构,且体系中阴离子的氢键碱性越弱,阳离子的烷基链越短,对胰岛素分子结构的稳定作用越强。并深入分析不同烷基链长度的二氰胺类离子液体与胰岛素之间的相互作用,发现相较于长烷基链离子液体,短烷基链离子液体与胰岛素之间的相互作用更强,揭示了后者能更好地维持和稳定胰岛蛋白的分子结构。     

Application of optical microscopy as a screening technique for cellulose and lignin solvent systems

Rapid and facile screening techniques to determine the effectiveness of solvents for cellulose or biomass dissolution can advance biomass processing research. Here, we report the use of a simple optical microscopy method to screen potential cellulose and lignin solvents. The described methodology was used to screen the dissolution of cellulose and lignin in two imidazolium‐based ionic liquids (ILs), two phosphonium‐based ILs, as well as a N,N‐dimethylacetamide/lithium chloride (DMAc/LiCl) solution in less time than other techniques. The imidazolium‐based ILs and the DMAc/LiCl were found to dissolve both cellulose and lignin. Also, it was observed that one of the phosphonium‐based ILs dissolved lignin and not cellulose, demonstrating a potential for biomass fractionation applications. © 2011 Canadian Society for Chemical Engineering     

离子液体降解性的研究进展

离子液体作为绿色溶剂,在电化学、有机化学、生物化学等领域获得了广泛重视,但目前研究主要集中于离子液体的合成和应用,而与环保问题直接相关的降解性方面的研究不足,实现离子液体的降解是离子液体大规模使用之前必须要解决的问题。本文综述了离子液体的降解方法:化学降解法和生物降解法。化学降解法主要通过UV/H₂O₂体系、Fe(Ⅲ)/H₂O₂体系、电解体系实现对离子液体的降解;生物降解法则通过引入可以提供酶解位点的基团,或者单加氧酶将离子液体阳离子烷基侧链甲基末端氧化为羟基、醛基,形成羧基,再进行β-氧化过程。提出了针对化学降解法和生物降解法机理的不同,需要对离子液体的化学结构进行设计、适当控制烷基侧链的长度、引入易降解的功能基团等;同时筛选微生物,进而提高离子液体的降解效率。     

内置换热器的不同工质ORC系统的综合评价分析

将换热器置于有机朗肯循环(organic Rankine cycle,ORC)系统,并结合不同工质对ORC性能进行研究。论文基于热效率、 效率、经济性能指标和热回收效率建立目标函数,通过线性加权法提出了一种新的综合评价指标,以此对加入内部换热器(IHE)的不同工质的ORC系统进行评价和分析,尤其是着重对工质为R123系统进行了分析。由于加入内部换热器后,经过膨胀机的较高温气体与经过循环泵的较低温气体换热,可知该系统可以降低预热工质所需能量的损耗,并通过分析改变蒸发冷凝温度使整个系统的综合性能得到了提高。     

多烷基咪唑离子液体的合成及性能比较

以咪唑或1,2-二甲基咪唑和卤代烷为原料,合成了4种多烷基咪唑类离子液体,以及6种1,3-二丁基咪唑和1-丁基-3-乙基咪唑类离子液体,产率较高。产物结构经核磁共振氢谱进行了确认。测定了产物水溶液的pH和不同浓度下的电导率,研究了烷基对离子液体酸性的影响,以及不同阴离子或烷基链长度对电导率的影响。测定了产物的吸湿性,结果表明,多烷基咪唑六氟磷酸盐离子液体具有较低的吸湿性。     

Recent trends in (ligno)cellulose dissolution using neoteric solvents: switchable,distillable and bio‐based ionic liquids

Recent years have witnessed the use of different ionic liquids for biomass processing, either at the level of lignocellulose pre‐treatment, to fractionate biomass in its main components, separating hemicellulose and lignin from cellulose, or directly in cellulose decrystallization by dissolving it in the ionic liquid and subsequent precipitation by adding anti‐solvents. Yet, most of the ILs employed in these strategies (e.g. imidazolium‐based solvents) are (still) expensive for such applications, and provide discussable ecological footprints. In an attempt to combine the highly useful generated knowledge with novel neoteric solvents with improved properties, economics, availability and ecology, several new trends have appeared in these areas during recent years. They comprise the use of switchable ILs, based on strong organic bases and CO₂, the application of distillable ILs, as well as the use of bio‐based and low‐cost ILs and deep‐eutectic‐solvents (DES), e.g. choline chloride‐based derivatives. Apart from other emerging uses, for all these solvents some preliminary applications in biomass processing involving pretreatments, cellulose dissolution and other applications have been successfully reported. This Minireview contextualizes these recent trends and discusses them with emphasis on future use of them in biorefineries and biomass valorization. © 2013 Society of Chemical Industry     

溴化1-乙烯基-3-烷基咪唑离子液体的电化学性能

合成了溴化1-乙烯基-3-烷基咪唑([VAIM]Br)离子液体,采用FTIR、¹H NMR、TG及DSC进行了表征,并系统研究了[VAIM]Br的电化学性能。结果表明:在298.15～323.15 K内,[VAIM]Br的电导率(σ)与温度符合Arrhenius方程,电导活化能随[VAIM]⁺上烷基链的增长而降低。分别以水、甲醇和乙醇为溶剂的[VAIM]Br溶液的电导率均随浓度的增大而显著增大,且σ(水)>σ(甲醇)>σ(乙醇)。通过电导法确定了[VAIM]Br在水、甲醇、乙醇中的临界胶束浓度,分别约为6.8×10^-6、1.5×10^-5、2.0×10^-5 mol·L^-1,表面活性优异。[VAIM]Br的电化学窗口在1.6～2.5 V,其电化学稳定性随[VAIM]⁺上烷基链的增长而逐渐降低。     

L-脯氨酸为阴离子的手性离子液体的合成、表征及光学活性

以L-脯氨酸为手性源,合成了四种烷基咪唑手性离子液体,并进行了结构表征。烷基咪唑溴化物离子液体经与氢氧化钾碱化后再与氨基酸中和反应制得产物,探索了合适的反应条件。测定了产物的比旋光度,考察了各产物的光学纯度。     

基于COSMO-RS模型的分离油酚混合物的离子液体萃取剂筛选

低温煤焦油中酚类化合物的分离对其充分利用具有重要意义。基于COSMO-RS模型,以间甲酚和异丙苯作为模型化合物,研究了离子液体在分离油酚体系中的应用;利用Turbomole软件建立了包含27种离子液体阴离子和48种离子液体阳离子的s-图谱数据库,结合COSMOtherm软件对组成的1296种离子液体进行筛选,探讨了阴阳离子对间甲酚分离效果的影响,并对筛选得到适宜的离子液体进行液液相平衡实验验证。结果表明,离子液体阴离子对间甲酚分离效果影响较大,以Cl^-和CH₃COO^-为阴离子的离子液体与间甲酚之间具有较强的氢键相互作用,因此具有较好的分离效果;阳离子对间甲酚分离效果影响较小,碳链或支链的增加能适当提高离子液体对间甲酚的分离效果。实验得到的bmimOAc、bmimCl、emimOAc、TPAC四种离子液体-间甲酚-异丙苯的液液相平衡数据表明,四种离子液体对间甲酚均具有较大的分配系数和选择性,且萃取分离效果的顺序为：emimOAc > bmimOAc > TPAC > bmimCl,与COSMO-RS模拟筛选得到的结果一致,表明筛选具有较高的准确性。     

基于COSMO-SAC模型的分子筛选方法用于咪唑类离子液体吸收甲苯蒸气

采用基于COSMO-SAC模型的分子筛选方法,对作为甲苯蒸气吸收剂的咪唑类离子液体进行了筛选。建立了100种常见的N,N'-二烷基咪唑阳离子与阴离子构成的咪唑类离子液体的s-谱图,在此基础上计算了303.15 K下离子液体对甲苯的吸收势,并以此为热力学评价标准对吸收剂进行筛选。选取6种离子液体进行甲苯蒸气的吸收实验,通过其饱和吸收量验证此方法的可行性。研究表明,实验和分子筛选结果相吻合。利用Gaussian 09软件进行微观结构分析,计算了离子液体阳离子与甲苯的相互作用能。对进气浓度和进气速度等动力学因素的影响进行探究,在条件为303.15 K、进气浓度为10000 mg·m^-3、进气速度为0.05 m³·h^-1情况下,离子液体对甲苯的初始吸收率高达96.2%。此外,实验验证了离子液体随着重复利用次数的增加,其吸收效果基本不变。     

Purification of undiluted ionic liquids from trace-colored impurities for spectroscopy by octadecylsilyl solid-phase extraction

Ionic liquids are often contaminated by trace-colored impurities. In this paper, a solid-phase extraction (SPE) method for purification of undiluted imidazolium ionic liquids was described. A SPE apparatus with octadecylsilyl (ODS) solid phase was proposed to separate these impurities from ionic liquids via hydrophobic interaction. Solid-phase extraction with ODS can improve the spectroscopic quality obviously for the tested ionic liquids. Without introducing any solvent to ionic liquid, the purified ionic liquid can be used directly in spectroscopic measurements. It was found that short alkyl chain ionic liquids were purified more efficiently than the long alkyl chain ones. This method can be used to purify the hydrogen-bonding anion containing ionic liquids, which cannot be decolorized efficiently by conventional active charcoal method. In comparison with other existing purification methods, ODS is advantageous to solve the purification problem of ionic liquids.     

离子液体；石油沥青质的新型溶剂

The dissolution of petroleum asphaltenes with ionic liquids is studied for the first time. The results show that the ionic liquids could be used as novel solvents for asphaltenes. The important parameters governing the ability of ionic liquids for dissolution of asphaltenes are discussed. It is found that, the ionic liquids based on the cations containing a conjugated aromatic core or the anions which are strong hydrogen bond acceptors are most effective, whereas the ionic liquids containing ＇non coordinating＇ anions such as [BF4]^- and [PF6]^- are nonsolvents for asphaltenes. Increase in the effective anion charge density enhances the ability of ionic liquids to break the extensive asphaltene associations and thus enhances the solubility of asphaltenes in the ionic liquid. The dissolution ability of ionic liquid decreases apparently with increasing the substituted alkyl chain length of its cationic head ring. Temperature is found to play an important role on dissolution of asphaltenes, and the dissolution can be significantly imoroved bv microwave heatinz.     

Effect of ionic liquids and surfactants on zinc oxide nanoparticle activity in crosslinking of acrylonitrile butadiene elastomer

The goal of this work was to study the influence of several ionic liquids and cationic surfactants on zinc oxide nanoparticle activity in sulfur vulcanization of acrylonitrile butadiene elastomer (NBR). In this article, we discuss the effect of ionic liquids and surfactants on the cure characteristics, crosslink density, and distribution in the elastomer network as well as on mechanical properties of the acrylonitrile butadiene rubber. Ionic liquids (alkylimidazolium salts) and cationic surfactants (alkylammonium bromides) decrease the vulcanization time of rubber compounds. Their application results in the increase of vulcanizate crosslink density as well as of the heterogeneity of elastomer network. The influence of ionic liquids on the acrylonitrile butadiene elastomer properties depends on the anion present in the molecule and on the length of alkyl chains attached to the imidazolium ring. The most active ionic liquids seem to be the ones with the 1‐butyl‐3‐methylimidazolium cation or the BF₄^‐ anion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Copolymerization of phenyl glycidyl ether with carbon dioxide catalyzed by ionic liquids

The copolymerization of phenyl glycidyl ether (PGE) and carbon dioxide was performed without any solvent in the presence of ionic liquid as catalyst. The reaction was carried out in a batch autoclave reactor. The carbonate content of polycarbonate was affected by the structure of imidazolium salt ionic liquid; the one with the cation of bulkier alkyl chain length and with more nucleophilic anion showed better reactivity. However, the yield of carbon dioxide addition decreased when hexyl or octyl containing ionic liquids were used in place of butyl group in 1-alkyl-3-methyl imidazolium salts. The carbonate content and turnover number (TON) of the polycarbonate increased as the reaction temperature increased from 40 to 80 ‡C. However, the carbonate content decreased with increasing reaction time.